This invention relates to a scum treating apparatus for removing a large quantity of scum drifting on the water surface in the starting or final sedimentation pond therefrom.
The applicant of this invention has developed and proposed a scum removing apparatus in connection with the movement of flights on the pond. The Utility Model Registration Application, No. 094729 (Application Date: June 22, 1965) discloses the abovesaid proposal.
An outline of this apparatus is as shown in FIG. 38. Support means 301 formed of a rubber sheet is disposed in front of a trough or scum receiving means 300 and a float or damming up means 302 is provided ahead of support means 301 so as to be raised above or lowered below the water surface 303. For raising or lowering the float, a horizontal lever shaft 304, which is one of the interlocking means, is provided on the water surface 303 of the pond and a lever-like arm 306, which is another one of the interlocking means and has a projecting part opposing the flight 305 and an extending part directed toward the float 302, is supported around the lever shaft 304 at the midpoint thereof. The lever-like arm 306 is provided with a cam part 306a which is still another one of the interlocking means and is so constructed as to be kicked up by the flight 305 coming closer thereto and, thereby, rotates to depress the float 302. When the flight 305 passes the cam part 306a, the lever-like arm 306 rotates in the initial direction and thus the float 302 rises above the water surface. With the repeat of such rising and lowering movement, the scum masses 307 are introduced into the trough 300 and removed outside (the other treating apparatus) through a path not shown.
The scam treating apparatus as above, however, suffers the following problems.
The cam 306a comprises one projecting portion so as to be liftedly moved one time by one time of the passage of the flight 305.
The sprockets driving the chain are arranged at two points in the vicinity of the surface 303 of the water and two points in the bottom portion of the basin, that is four points in all, and the flight 305 passing between two sprockets on the upper side is operated so as to collect the scum 307 on the surface 303 of the water toward the trough 300, as is shown in FIG. 38. However, subsequently, the flight 305 makes progress in a oblique-downward direction to the lower sprocket to be submerged under the surface of the water according to the conditions of the disposal pond, so that the scum 307 cannot be sufficiently positively collected toward the trough 300.
Furthermore, in this type of settling basin, the cam 306a operates one time in the above described manner so that, although the scum 307 close to the front of the float 302 can be introduced into the trough 300, the scum 307 far from the float cannot be skillfully and efficiently guided to the trough 300 since the flow speed is reduced.
As a result, effective introduction of the scum masses 307 into the trough 300 is hardly possible. With a degree of depressing the float 302 set small, the flowing speed is raised and the scum masses 307 distant from the float can be introduced to the vicinity of the float 302. However, on the contrary, the large scum masses 307 touching the float 302 and staying thereat are prevented from being introduced into the trough 300 and, therefore, a quantity of the scum masses to be collected decreases to a large extent.
Further, the cam 306a, if formed into one body with the lever-like arm 306, the whole of the arm 306 must be replaced when the cam 306a has greatly worn, thereby requiring much labor for maintenance and high cost for replacement. When leaving wear of the cam 306a as it is, the degree of depressing the float 302 is reduced and effective introduction of the scum masses 307 . . . into the trough 300 becomes impossible.
In addition, as other problems, it has been found from experiment that, since the float 302 is circular in cross section and hollow, the large scum masses 307 flowing downstream ride on and stay at the upper curved surface of the float 302 as shown in FIG. 39, when subsequent masses 307, too, are prevented from flowing further.